The wheel lug thread size is M12 x 1.5. My 16" alloy wheels have very tight lug nut recesses so I got "tuner style" locks from McGard stock # 25257 from Amazon.
I got my wheels from discounttiredirect.com and was happy with their selection and prices. You can use the website to see what the wheels will look like on your car. Free shipping too. I got their splined lug nuts so in addition to my locks (1 lock per wheel), the other 4 lug nuts on each wheel also need a key.
I was able to get a discount from my local Discount Tire store when I mounted my stock 16" tires onto my new wheels. I had them transfer my TPMS sensors from my stock wheels to my new wheels.
I sold my stock wheels and wheel covers on Craigslist.